Clutch release bearing with self-alignment by means of elastic sleeve

ABSTRACT

The invention concerns a clutch release bearing comprising an engaging element capable of co-operating with a clutch diaphragm ( 29 ), and designed to be mounted on a manoeuvring element ( 2 ) mobile in translation under the action of a control member ( 6 ). The engaging element comprises a roller bearing ( 1 ) provided with a rotating ring ( 13 ) and a non-rotating ring ( 9 ), said engaging element being radially mobile relative to the manoeuvring element to be self-aligned by means of a radially elastic self-aligning sleeve ( 19 ), arranged in the bore of the non-rotating ring to co-operate with the manoeuvring element. The roller bearing is of the standard type comprising an outer peripheral surface and a cylindrical bore axially defined by two parallel radial surfaces, and at least a seal joint ( 18 ) mounted on one of the rings and in friction contact with the other ring, the sleeve comprising sealing means co-operating with a rotating part of the engaging element.

The present invention relates to the field of clutch-release bearings,particularly for motor vehicles, of the kind comprising an operatingelement able to move in translation under the action of a control membersuch as a clutch-release fork or the piston of a hydraulic control, athrust rolling bearing intended to act on the clutch-release device of aclutch, such as a diaphragm, and, between the thrust bearing and theoperating element, a self-alignment elastic connecting member providingan axial connection between the thrust bearing and the operating elementand allowing the thrust bearing to self-centre with respect to thediaphragm if the axis of the diaphragm and the axis the thrust bearingare not exactly coincident at the time of mounting. Such a releasebearing is described, for example, in document FR-A-2 663 702.

The rings of thrust rolling bearings are made of pressed sheet metal.The inner ring comprises a radial portion extending outwards in contactwith a radial flange of the operating element. The outer ring comprisesa radial portion extending inwards for contact with the diaphragm.

The self-alignment elastic connecting member consists or an elasticsleeve lying between he bore of the non-rotating ring of the thrustbearing and a cylindrical bearing surface of the operating element. Thesleeve, generally made of elastomere or of some equivalent flexiblematerial, comprises in its bore a number of ribs which protrude radiallywith respect to the bore and run axially along he length of the sleeve.These ribs are slightly inclined and have the shape of leaves, the freeends of which rest against the cylindrical bearing surface of theoperating member.

The ribs can thus deform and allow the bearing to move radially withrespect to the operating element to self-align on the diaphragm duringoperation.

The self-alignment elastic connecting member is axially secured to thenon-rotating ring of the thrust bearing by complementary shapes, bymeans of a radial flange or of an annular bore situated at its rear end,opposite the diaphragm, and collaborating with a stepped part of thebore of the ring, and of an annular groove formed at its front end andcollaborating through complementary shapes with a radial return or theinner ring. An annular bore protecting from the front free end of theoperating element forms an axal stop for the axial end of the ribs ofthe sleeve. The axial end of the sleeve is provided with a sealing lipin rubbing contact with the radial portion of the outer ring.

Sealing makes it possible, on the one hand, to avoid losing the greasewhich is used to lubricate the rolling bearing and, on the other hand,to prevent the ingress of foreign particles likely to contaminate theinside of the bearing. A sealing flange is arranged at the rear of thebearing and a sealing lip coming from the self-alignment elastic sleevecollaborates at the front of the thrust bearing with a surface of therotating ring.

While this type of thrust bearing is satisfactory in most cases, it canhappen that in certain applications and conditions of use which areextremely harsh in terms of contamination, the sealing may proveinsufficient and result in the ingress of contaminants which affect thecorrect lubrication of the rolling bearing and thereby shorten the lifeof said rolling bearing.

It is not straightforward, In thrust rolling bearings in which the ringsare made of pressed sheet metal, to arrange seals, particularly rubbingseals, very effectively because the often complex shapes and thegeometric qualities of the pressed sheet metal rings often make theattachment of such seals awkward.

Furthermore, the quality of the surfaces which act as rubbing surfacesfor the lips of the seals is not always very good.

The present invention aims to solve these problems by proposing acompact economical thrust bearing with a low number of parts and whichis equipped with effective sealing means.

The clutch-release bearing device of the present invent is of the typecomprising an engaging element capable of collaborating with a clutchdiaphragm. The engaging element is intended to be mounted on anoperating element able to move in translation under the action of acontrol member, the engaging element comprising a rolling bearingprovided with a rotating ring and with a non-rotating ring, the saidengaging element being able to move radially with respect to theoperating element to allow it to self-align with respect to thediaphragm by virtue of a radially elastic self-alignment sleeve arrangedin the bore of the non-rotating ring to collaborate with a bearingsurface of the operating element. The bearing is of the conventionaltype comprising an outer peripheral surface and a bore which arecylindrical and bounded axially by two radial parallel faces, and atleast one seal mounted on one of the rings and in rubbing contact withthe other ring, the sleeve comprising a sealing means capable ofcollaborating with a rotating part of the engaging element.

As a preference, the engaging element comprises an engaging piecesecured to the rotating ring and able to come into contact with thediaphragm, the sealing means of the sleeve rubbing against a surface ofthe engaging piece.

In one embodiment of the invention, the engaging piece is integral withthe rotating ring.

In one embodiment of the invention, the sealing means of the sleevecomprises a lip formed as an integral part of the said sleeve.

In one embodiment of the Invention, the sealing means of the sleevecomprises a means for forming a narrow passage with a rotating surfaceof the engaging element.

In one embodiment of the invention, the sleeve is made of rubber.

In one of the embodiment of the invention, the sleeve comprises a metalinsert in contact with the non-rotating ring.

Advantageously, the narrow passage is formed between one end of theinsert and the engaging element.

Advantageously, the bearing seal is in rubbing contact with asurface-ground surface of the said other ring.

In one embodiment of the invention, the bearing comprises two seals.

In one embodiment of the invention, the sealing means of the sleevecomprises a lip able to come into contact with a rotating surface of theengaging element and a means for forming a narrow passage with anotherrotating surface of the engaging element.

Thus, the seals of the rolling bearing come into contact withsurface-ground surfaces, hence giving very good quality sealingextending the life of the bearing. The sealing means of the sleeve makethe ingress of contaminants into the space defined by the engaging pieceand the rolling bearing, and therefore into the inside of the rollingbearing, all the more difficult.

The present invention will be better understood and other advantageswill become apparent upon reading the detailed description of someembodiments taken by way of entirely non-limiting examples andillustrated by the appended drawings, in which:

FIG. 1 is a view in axial section of a thrust rolling bearing accordingto the invention;

FIG. 2 is a view in cross section of the sleeve of the thrust rollingbearing of FIG. 1; and

FIG. 3 is a view similar to FIG. 1 of another embodiment of theinvention.

As illustrated in FIG. 1, the clutch-release bearing according to theinvention comprises a rolling bearing 1 mounted on an operating element2 which comprises a tubular portion 3 which car slide with respect to aguide tube 5 and a radial flange 4. The radial flange 4 of the operatingelement 2 is formed of a metal annulus over which the tubular portion 3is moulded. The radial flange 4 has preferably undergone a surfacehardening treatment, and acts as a contact surface for a control member6 of the fork type and which exerts a force in an axial direction tocause the thrust bearing to move in its entirety during theclutch-release operation.

Two radial portions 7 and 8, integral with the tubular portion 3, arearranged one on each side of the radial flange 4, while at the same timehaving markedly smaller radial dimensions. The radial portion or 7 has aradial surface 7 a against which the rolling bearing 1 bears. The radialportion 8 is arranged on the same side as the control member 6.

The rolling bearing 1 comprises an inner ring 9 having a toric raceway10 for a row of rolling elements 11, for example balls, held in a cage12. The inner ring 9 comprises a bore 9 a, two radial frontal surfaces 9b and 9 c and a cylindrical external surface 9 d in which the raceway 10has been formed. The bore 9 a, the two radial frontal surfaces 9 b and 9c forming the two faces of the ring, the cylindrical surface 9 d and theraceway 10 are obtained by surface grinding, with an additional lappingoperation in the case of the raceway 10.

The rolling bearing 1 is supplemented by an outer ring 13 which has atoric raceway 14 for the rolling elements 11. The outer ring 13comprises a bore 13 a in which the raceway 14 has been formed, tworadial frontal surfaces 13 b and 13 c and a cylindrical external surface13 d. The cylindrical external surface 13 d, the frontal surfaces 13 band 13 c and the raceway 14 are obtained by surface grinding wish anadditional lapping operation in the case of the raceway. Also formed inthe bore 13 a, are two annular grooves 15 and 16, each adjacent to oneof the frontal surfaces 13 b, 13 c. A seal 17 is mounted in the groove15 and comprises an elastic part extending from he groove 15 to theexterior surface 9 d of the inner ring 9, ending in a rubbing lip, and arigid part, for example a metal armature in the shape of a washer, whichis radially shorter. A seal 18 identical to tie seal 17 is mounted inthe groove 16.

The rings of the rolling bearings of conventional type are not made fromblanks obtained by pressing a sheet metal strip.

They are obtained from tubes, bars or from forged blanks, by turning orhot or semi-hot forming, heat treatment, surface grinding offunctionally flat, cylindrical or toric surfaces, and finally by lappingcertain parts such as the raceways.

A self-alignment sleeve 19 is arranged between the tubular portion 3 andthe bore 9 a of the inner ring 9. The elastic sleeve 19, made, forexample, of elastomer or of natural rubber, has a number ofself-alignment ribs 20 parallel to the axis of the thrust bearing anddirected towards the inside and the internal free edges of which comeinto contact with the exterior surface 3 a of the tubular portion 3 ofthe operating element 2 which surfaces are made of rigid syntheticmaterial, for example of synthetic material to which inorganic fillersor the like have been added.

The elastic sleeve 19 comprises an annular metal armature 21 providedwith a cylindrical portion 22 arranged axially at the inner ring 9 ofthe bearing and pushed into the bore 9 a and with a radial portion 23extending the cylindrical portion 22 on the opposite side to the radialflange 4, facing outwards and increasing the rigidity of the armature.It can be seen that the axial lengths of the cylindrical portion 22 andof the inner ring 9 are identical and that the radial portion 23 is incontact with the frontal surface 9 b. The cylindrical portion 22 and theradial portion 23 of the armature 21 are covered by the elastic materialof the sleeve 19.

The elastic sleeve 19 comprises an annular lip 24 formed in the saidelastic material and which seals the rolling bearing 1 by extendingaxially away from the radial flange 4 from the radial portion 23 of themetal armature 21. An annular rib 25 arranged at the end of thecylindrical portion 3 holds the rolling bearing 1 axially on theoperating element 2. The sleeve 19 is also pushed onto the non-rotatingring 9 where it remains perfectly centered and held. Its axial positionis guaranteed by the contact between the frontal surface 9 c of the ring9 and the surface 7 a of the radial portion 7.

The rolling bearing 1 comprises an engaging element 26, for example madeof pressed and treated sheet metal, a cylindrical part 27 of which ispushed onto the exterior surface 13 d of the outer ring 13 and alsocomprises a roughly radial part 28 extending towards the inside from thecylindrical portion 27 as far as the sleeve 19. A clutch diaphragm 29,or an element of the same kind, is in contact with the radial portion 28on the opposite side to the bearing. The sealing lip 24 rubs against theradial portion 28 on the same side as the rolling bearing.

Thus, on the same side as the diaphragm 29, sealing is twofold, with thelip 24 of the sleeve 19 rubbing against the surface of the engagingpiece 26, and the seal 17 the lip of which rubs against the exteriorsurface 9 d of the inner ring 9. On the opposite side, sealing isprovided by the seal 18. The rotating part is formed by the outer ring13 and the engaging piece 26. The non-rotating part is formed by theinner ring 9. The two parts, rotating and non-rotating, form theengaging element 1 which is mounted on the operating element 2 via theself-alignment sleeve 19.

It would be possible, without departing from the scope of the invention,to envisage the engaging piece 26 being integral with the outer ring ofthe bearing, the said engaging piece then being in the form of a simpleaxial extension of the rotating outer ring on one of its sides.

The embodiment illustrated in FIG. 2 is similar to the previous oneexcept that the metal armature 21 of the sleeve 19 comprises acylindrical portion 30 extending from the free end of the radial portion23 towards the diaphragm 29. The sleeve 19 comprises a sealing lip 31extending towards the diaphragm 29 and radially extending slightlyoutwards from a region lying radially between the ribs 20 and the bore 9a of the inner ring 9.

The radial part of the engaging piece 26 is replaced by a rounded part32 which is convex on the side of the diaphragm 29, and which ends in acylindrical free end 33 radially level with the inner ring 9 and axiallyadjacent to the radial portion 23 of the armature 21.

The free end 33 of the engaging piece 26 is surrounded on the inside bythe lip 31 which rubs on It and on the outside by the cylindricalportion 30 of the armature 21 with which it forms a narrow passage. Thistwofold sealing makes it possible to further improve the sealingperformance or, as an alternative, to omit the seal 17 of FIG. 1, inorder to reduce the cost.

The combination of a sealed conventional rolling bearing with aself-alignment sleeve what has radial elasticity therefore gives thepossibility of producing a clutch-release bearing with better sealingconsisting of the sealing inherent to the rolling bearing and theadditional sealing resulting from the self-alignment sleeve.

What is claimed is:
 1. A clutch-release bearing device comprising anoperating element and an engaging element capable of collaborating witha clutch diaphragm, the engaging element being intended to be mounted onthe operating element able to move in translation under the action of acontrol member, the engaging element comprising a rolling bearingprovided with a rotating ring and with a non-rotating ring, the engagingelement being able to move radially with respect to the operatingelement to allow it to self-align with respect to the diaphragm byvirtue of a radially elastic self-alignment sleeve arranged in the boreof the non-rotating ring to collaborate with a bearing surface of theoperating element, the bearing comprising an outer peripheral surfaceand a bore which are cylindrical and bounded axially by two radialparallel faces, and at least one seal mounted on one of the rings and inrubbing contact with the other ring, the sleeve comprising a sealingmeans capable of collaborating with a rotating part of the engagingelement.
 2. The device according to claim 1, wherein the engagingelement comprises an engaging piece secured to the rotating ring andable to come into contact with the diaphragm, the sealing means of thesleeve rubbing against a surface of the engaging piece.
 3. The deviceaccording to claim 2, wherein the engaging piece is integral with therotating ring.
 4. The device according to claim 1, wherein the sealingmeans of the sleeve comprises a lip formed as an integral part of thesaid sleeve.
 5. The device according to claim 1, wherein the sealingmeans of the sleeve comprises a means for forming a narrow passage witha rotating surface of the engaging element.
 6. The device according toclaim 1, wherein the sleeve is made of rubber.
 7. The device accordingto claim 1, wherein the sleeve comprises a metal insert in contact withthe non-rotating ring.
 8. The device according to claim 7, wherein thesealing means of the sleeve comprises a narrow passage that is formedbetween one end of the insert and a rotating surface of the engagingelement.
 9. The device according to claim 1, wherein the bearing seal isin rubbing contact with a surface-ground surface of the said other ring.10. The device according to claim 1, wherein the bearing comprises twoseals.
 11. The device according to claim 1, wherein the sealing means ofthe sleeve comprises a lip able to come into contact with a rotatingsurface of the engaging element and a means for forming a narrow passagewith another rotating surface of the engaging element.